Nuclear Magnetic Resonance (NMR) imaging machines have recently been developed to provide images of the head and body similar to those produced by x-ray CT scanners, and a prototype NMR images is to be installed in our institution in January 1983. Phantoms for quantitatively evaluating imaging performance and for routine quality control have proved invaluable in x-ray CT, and were also useful in determining which parameters were the most important for CT imaging (e.g., low contrast resolution). Phantoms for NMR imaging will certainly be just as important as for x-ray CT, and possibly more so due to the greater flexibility in selecting imaging parameters in NMR. We propose to develop materials which simulate the NMR characteristics of tissues and to make phantoms from these materials which can be used to quantitatively test the imaging performance of NMR imagers. The proton density Rho, the spin-lattice and spin-relaxation times (T1, T2) of the phantom materials will be measured in an independent NMR spectrometer operating at the same frequency as the imager. Hardened and stabilized gels doped with fats and trace paramagnetics, in order to mimic (Rho, T1, T2) of tissue, will be used. Phantoms will be constructed which have low contrast inserts, those inserts differing by a small (but known) percentage from their surroundings in either Rho, T1, T2. In this way we can determine how small an object the imager can detect at a given percentage contrast. Those imaging pulse protocols which produce the best low-contrast resolution on phantoms will be tested in the clinical arena by the radiologists. The accuracy of the imager in determining T1 values will also be determined so that the imager can be used for in-vivo T1 measurements on cancerous tissues with confidence. Spatial resolution and noise/uniformity phantoms will also be constructed and evaluated. The phantoms thus developed can be used by the radiology community to evaluate the relative performance of the various NMR imaging machines soon to be introduced into the marketplace. Correlating the clinical imaging pulse protocols with the degree of low contrast resolution in (Rho, T1, T2) that they provide will help in discovering which parameters are important, and to what degree, in NMR imaging.